Bathymetric Surveys of Morse and Geist Reservoirs in Central Indiana Made with Acoustic Doppler Current Profiler and Global Positioning System Technology, 1996

By JOHN T. WILSON, SCOTT E. MORLOCK, and NANCY T. BAKER

Prepared in cooperation with the INDIANA DEPARTMENT OF NATURAL RESOURCES, DIVISION OF WATER

U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 97-4099

Indianapolis, Indiana 1997 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director

The use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

For additional information, write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services Water Resources Division Box 25286 5957 Lakeside Boulevard Federal Center Indianapolis, IN 46278-1996 Denver, CO 80225 CONTENTS

Abstract ...... 1 Introduction ...... 1 Purpose and Scope ...... 2 Physical Setting ...... 2 Morse Reservoir ...... 2 Geist Reservoir ...... 4 Acknowledgments ...... 4 Methods of Investigation ...... 4 Acoustic Doppler Current Profiler ...... 5 Operation Principles ...... 5 Operation Limitations ...... 8 Accuracy of Acoustic Doppler Current Profiler Methods ...... 9 Global Positioning System ...... 10 Operation Principles ...... 10 Operation Limitations ...... 11 Accuracy of Global Positioning System Methods ...... 11 Bathymetric Surveys ...... 11 Contour Mapping ...... 16 Contour Map Generation...... 16 Contour Mapping Limitations ...... 17 Estimation of Reservoir Volumes ...... 20 Morse Reservoir ...... 20 Geist Reservoir ...... 20 Estimation of Sedimentation ...... 20 Morse Reservoir ...... 21 Geist Reservoir ...... 22 Summary and Conclusions ...... 23 References Cited ...... 24 Supplemental Data...... 25 Cross Sections of Morse Reservoir ...... 25 Cross Sections of Geist Reservoir ...... 37

FIGURES 1-2. Maps showing: 1. Location of Morse and Geist Reservoirs in Hamilton and Marion Counties, Indiana...... 3 2. Example of the pattern of boat paths used to collect bathymetry data with the acoustic Doppler current profiler and a global positioning system on Geist Reservoir, central Indiana...... 6 3. Sketch showing the components of a typical acoustic Doppler current profiler and sketch of an ADCP mounted on a boat...... 7 4. Graphs showing a comparison of average water depth from the acoustic Doppler current profiler with water depth from a survey rod on Geist and Morse Reservoirs, central Indiana, and a comparison of the difference in water depths between the two methods and the water depth from a survey rod...... 9

Contents Hi CONTENTS

FIGURES Continued 5-8. Maps showing: 5. Location of acoustic Doppler current profiler transects, shallow-water-depth points, and cross sections for Morse Reservoir, central Indiana ...... 14 6. Location of acoustic Doppler current profiler transects, shallow-water-depth points, and cross sections for Geist Reservoir, central Indiana ...... 15 7. Water-depth contours of Morse Reservoir, central Indiana...... 18 8. Water-depth contours of Geist Reservoir, central Indiana...... 19 9-19. Graphs showing cross sections of Morse Reservoir, central Indiana, from a 1978 fathometer profile and a cross section from the bathymetric surface computed from the 1996 survey: 9. Cross section #2 ...... 26 10. Cross section #3 ...... 27 11. Cross section #5 ...... 28 12. Cross section #6 ...... 29 13. Cross section #8 ...... 30 14. Cross section #10...... 31 15. Cross section #12 ...... 32 16. Cross section #14 ...... 33 17. Cross section #16 ...... 34 18. Cross section #18 ...... 35 19. Cross section #20 ...... 36 20-31. Graphs showing cross sections of Geist Reservoir, central Indiana, from a 1980 fathometer profile and a cross section from the bathymetric surface computed from the 1996 survey: 20. Cross section #1 ...... 38 21. Cross section #7 ...... 39 22. Cross section #8 ...... 40 23. Cross section #12 ...... 41 24. Cross section #15 ...... 42 25. Cross section #20 ...... 43 26. Cross section #26 ...... 44 27. Cross section #29 ...... 45 28. Cross section #33 ...... 46 29. Cross section #36 ...... 47 30. Cross section #37 ...... 48 31. Cross section #39 ...... 49

TABLES 1. Comparison of redundant global positioning system positions for evaluating the reproducibility of the GPS methods used to map Morse and Geist Reservoirs in central Indiana ...... 12 2. Comparison of measured global positioning system positions with known control points for evaluating the accuracy of the GPS methods used to map Morse and Geist Reservoirs in central Indiana...... 13 iv Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

Multiply By To Obtain

inch (in.) 25.4 millimeter foot (ft) 0.3048 meter square foot (ft2) 0.09290 square meter foot per second (ft/sec) 0.3048 meter per second mile (mi) 1.609 kilometer square mile (mi2) 2.590 square kilometer acre 4,047 square meter acre-feet (acre-ft) 1,233.5 cubic meter gallon (gal) 3.785 liter gallon (gal) 0.003785 cubic meter

Acre-foot: In this report, an acre-foot is the volume of water occupied by a depth of 1 foot over an area of 1 acre, which equals 43,560 cubic feet or approximately 326,000 gallons.

Knot: In this report, "knot" refers to nautical miles per hour, which equals about 1.15 statute miles per hour.

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929.

The following abbreviations are used in this report: Abbreviation Description ADCP Acoustic Doppler current profiler GIS Geographic information system GPS Global positioning system SA Selective Availability UTM Universal Transverse Mercator

kHz Kilohertz

m meter cm centimeter cm/sec centimeter per second km kilometer

Bgal Billion gallons Mgal Million gallons

Contents v Bathymetric Surveys of Morse and Geist Reservoirs in Central Indiana Made with Acoustic Doppler Current Profiler and Global Positioning System Technology, 1996

By John T. Wilson, Scott E. Morlock, and Nancy T. Baker

Abstract a surface area of 1,848 acres. The computed 1996 reservoir volumes are less than the Acoustic Doppler current profiler, global design volumes and indicate that sedimenta­ positioning system, and geographic informa­ tion has occurred in both reservoirs. Cross tion system technology were used to map the sections were constructed from the computer- bathymetry of Morse and Geist Reservoirs, generated surfaces for 1996 and compared to two artificial lakes used for public water sup­ the fathometer profiles from the 1978 and 1980 ply in central Indiana. The project was a pilot surveys; analysis of these cross sections also study to evaluate the use of the technologies indicates that some sedimentation has occurred for bathymetric surveys. Bathymetric surveys in both reservoirs. were last conducted in 1978 on Morse Reser­ voir and in 1980 on Geist Reservoir; those The acoustic Doppler current profiler, surveys were done with conventional methods global positioning system, and geographic using networks of fathometer transects. The information system technologies described 1996 bathymetric surveys produced updated in this report produced bathymetric maps and estimates of reservoir volumes that will serve volume estimates more efficiently and with as base-line data for future estimates of storage comparable or greater resolution than conven­ capacity and sedimentation rates. tional bathymetry methods. An acoustic Doppler current profiler and global positioning system receiver were used INTRODUCTION to collect water-depth and position data from April 1996 through October 1996. All water- Morse and Geist Reservoirs in central Indiana depth and position data were imported to a are used primarily for public water supply and geographic information system to create a data secondarily for recreation. The Indianapolis Water Company (IWC), which owns the reservoirs, and base. The geographic information system then the Indiana Department of Natural Resources was used to generate water-depth contour (IDNR) recognized the potential for sedimentation maps and to compute the volumes for each to affect the capacity of the two reservoirs and the reservoir. need for data to assess the status of sedimentation in them and their current capacity. The computed volume of Morse Reservoir The IDNR is mandated by the 1983 was 22,820 acre-feet (7.44 billion gallons), Water Resource Management Act to assess water- with a surface area of 1,484 acres. The resource availability, water use, and conflicts computed volume of Geist Reservoir was involving limited water supply or competing uses 19,280 acre-feet (6.29 billion gallons), with (Indiana Department of Natural Resources, 1994).

Abstract 1 IDNR has been assessing water availability on a sedimentation. Methods of data collection and data regional scale by major drainage basin. Informa­ processing, as well as the use of a geographic tion on the current capacities of Morse and Geist information system (GIS) to compute reservoir Reservoirs will be important to the assessment of volumes and generate water-depth contour maps water availability in the White River Basin. (hereafter referred to as "contour maps"), are In 1996, the U.S. Geological Survey (USGS), described. Reservoir volumes computed from the in cooperation with the IDNR Division of Water, bathymetry measured in 1996 are used to estimate began bathymetric surveys of Morse and Geist the reduction in storage capacity caused by sedi­ Reservoirs. A pilot study was incorporated into mentation. The 1996 volumes are compared to the the survey to evaluate the use of acoustic Doppler original design volumes and bathymetric surveys current profiler (ADCP) and global positioning from 1978 (Morse) and 1980 (Geist) to estimate system (GPS) technology. Bathymetric surveys the volume of sediment deposited in the reservoirs. were last conducted on Morse Reservoir in 1978 The bathymetric surveys described in this and on Geist Reservoir in 1980; those surveys were report will serve as base-line data for future esti­ made with conventional methods using networks mates of storage capacity and sedimentation rates of fathometer transects. in Morse and Geist Reservoirs. The bathymetric Conventional methods of collecting bathyme­ data will be stored in a GIS data base that will try data usually involve measuring water depths allow for comparisons with bathymetric data along a set of cross sections with a sounding device collected in the future. The methods and results or a fathometer. With the recent development and from using ADCP, GPS, and GIS technology availability of new technologies such as the ADCP described in this report demonstrate that bathymet­ and GPS, the scope and quality of bathymetric ric maps can be produced and reservoir volumes surveys can be increased while the time to produce can be estimated faster and with greater resolution bathymetry maps and reservoir volumes is de­ than with conventional bathymetry methods. creased. Also, the use of a geographic information system (GIS) to develop a data base, make maps, and compute reservoir volumes will increase the Physical Setting efficiency of bathymetry work. The use of a GIS also facilitates storage and retrieval of the data Morse and Geist Reservoirs are large artificial for future reference. lakes in central Indiana (fig. 1) that began opera­ tion in March 1956 and March 1943, respectively An awkward and time-consuming requirement (Thomas Brims, Indianapolis Water Company, of conventional bathymetric surveys is the need to written commun., 1996). The Indianapolis Water accurately track the survey-boat position. This is Company operates these reservoirs for public usually done by stringing tag lines across the body water supply. Recreation is a secondary use. of water or by surveying the boat position from The land use in the drainage basins above both shore. The ADCP used for this project's bathymet­ reservoirs is primarily agricultural. ric surveys was mounted in the survey boat and provided depth and position data throughout the reservoirs in water depths ranging from 2 to more Morse Reservoir than 40 ft. With the use of GPS, boat positions were converted into "real-world" coordinates for Morse Reservoir is in north-central Hamilton making contour maps with a GIS. County, 3.2 mi northwest of Noblesville and approximately 22 mi north-northeast of Indianapo­ lis, and is formed by the impoundment of Cicero Purpose and Scope Creek. The reservoir has a design storage capacity of 25,380 acre-ft (8.27 Bgal) at normal pool eleva­ The purpose of this report is to describe and tion; a surface area of approximately 1,500 acres; evaluate the use of ADCP and GPS technology for and approximately 32.5 mi of shoreline (Thomas bathymetric surveys and to estimate the reduction Bruns, Indianapolis Water Company, written in storage capacity in the reservoirs because of commun., 1996).

2 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 86°07'30"

North

Base from U.S. Geological Survey digital data, 1:100,000 1983 Albers Equal Area projection Standard parallels 29°30" and 45°30", central meridian -86° 0

4 6 KILOMETERS

Figure 1. Location of Morse and Geist Reservoirs in Hamilton and Marion Counties, Indiana. Physical Setting 3 Normal pool elevation is 810 ft above sea level. of feet. Control points were established at various The reservoir is approximately 6.5 mi long and locations along a transect, usually at the tip of a varies in width from several hundred feet to more boat dock, at an anchored buoy, or with a marker than 2,000 ft. Cicero Creek has a drainage area buoy. (For purposes of this report, a "transect" of 214 mi2 at Morse dam (Hoggatt, 1975). refers to the path of the ADCP as it collected bathymetric data.) A hand-held GPS receiver was Geist Reservoir used to determine the latitude and longitude of Geist Reservoir is in northeastern Marion the control points. County and southeastern Hamilton County, ARC/INFO GIS software from Environ­ approximately 14 mi northeast of Indianapolis, mental Systems Research Institute (ESRI) of and is formed by the impoundment of Fall Creek. Redlands, Calif., was used to transform the values The reservoir has a design storage capacity of of Northing and Easting into Universal Transverse 21,180 acre-ft (6.9 Bgal) at normal pool elevation; Mercator (UTM) coordinates. Northing and East­ a surface area of approximately 1,900 acres; and approximately 35 mi of shoreline (Thomas Bruns, ing for every depth point along the transect was Indianapolis Water Company, written commun., transformed into UTM coordinates based on the 1996). Normal pool elevation is 785 ft above sea coordinates of the control points, creating digital level. The reservoir is approximately 6.5 mi long data sets in ARC/INFO called point "coverages" and varies in width from approximately 1,000 to for each transect. A coverage is ARC/INFO's 4,000 ft. Fall Creek has a drainage area of 215 mi2 primary method for storing point, line, and area at Geist dam (Hoggatt, 1975). features. Coverages contain spatial (location) and attribute (descriptive) data. Coverages are typically Acknowledgments a single set of geographic features, such as points (Environmental Systems Research Institute, Inc., The authors thank the staffs of Geist and 1994). The ARC/INFO point coverages were used Morse Marinas of the Marina Limited Partner­ for making contour maps and estimating reservoir ship who were extremely helpful with solving volumes. mechanical problems, providing launch facilities, and providing a place to moor the USGS research Because of the reservoirs' size, a large number vessel. The authors also thank Thomas Bruns of of transects were required for the collection of ade­ the Indianapolis Water Company for providing quate data to represent accurately the bathymetry background information on the reservoirs and for of the reservoirs and to provide adequate data cov­ providing information from previous bathymetric erage for computer contouring. Data were collected surveys of Morse and Geist Reservoirs. from April 1996 through October 1996; data were collected for about 15 days on Morse Reservoir METHODS OF INVESTIGATION and about 19 days on Geist Reservoir. Data were collected so that a plot of the transects in the main The bathymetry of the reservoirs was mapped body and larger bays of the reservoir would by use of a boat-mounted ADCP and a mobile approximate a grid (fig. 2). The pattern of transects hand-held GPS receiver; detailed descriptions of varied in smaller bays because the maneuverability each method are located in the "Acoustic Doppler of the boat was limited. Transects were collected Current Profiler" and the "Global Positioning close to and roughly parallel to the shoreline, System" sections of this report. The ADCP except where water was too shallow for the ADCP was used to measure depth and position as the boat moved around the reservoirs. Position was to operate. Transects were collected in a zigzag or recorded as Northing and Easting, in feet, relative "S-turn" pattern along the length of the reservoir to the point where the ADCP began recording section being mapped, often with the same GPS bathymetric data. Depth also was recorded in units control points as the transects along the shoreline.

4 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 Transects also were collected along the length Acoustic Doppler Current Profiler of the reservoir, farther from shore but roughly parallel to the shoreline or perpendicular to the In 1992, RD Instruments introduced a broad­ transects collected in the S-turn pattern (fig. 2). band acoustic Doppler current profiler (ADCP) that Use of common GPS control points was helpful uses acoustic pulses (called "pings") to measure because the amount of time necessary to collect water velocities and depths. The manufacturer's GPS readings was reduced, transects could be specifications for these instruments indicate the instruments would have sufficient resolution and related to each other, and potentially inaccurate precision to permit their use in making river- GPS points could be identified when the transects discharge measurements in water as shallow as were converted into ARC/INFO coverages. 4 ft. The USGS Indiana District Office has been In large areas with shallow water, depth using an ADCP routinely since 1993 to measure soundings were made manually with a standard discharge in rivers. Morlock (1996) evaluated surveying rod. (The ADCP has a shallow depth ADCP measurements of river discharge and con­ limitation of approximately 2 feet if the lake cluded that the ADCP produced results comparable to conventional methods of measuring discharge. bottom is free of aquatic vegetation, rocks, and Because the ADCP measured boat position as logs.) The GPS receiver was used to record a well as water depth, it became apparent that the latitude and longitude for each of the soundings. ADCP could be used for applications other than These point depths were used to augment the measuring discharge, such as bathymetry. Recent ADCP bathymetry and improve the computer upgrades in the ADCP firmware have reduced the interpolations in shallow areas between the shallow-water limit to less than 2 ft. The following shoreline and deeper water. sections on "Operation Principles" and "Operation The values of depth are adjusted to normal Limitations" are based on Morlock (1996). pool elevation. Lake levels were recorded during each day of data collection by measuring the dis­ Operation Principles tance from reference marks to the water surface. Reference marks were established at two bridge The main external components of an ADCP crossings on each reservoir. are a transducer assembly and a pressure case (fig. 3). The transducer assembly consists of four ARC/INFO coverages of the shorelines transducers that operate at a fixed, ultrasonic of both reservoirs were established by digitizing frequency, typically 300 to 1200 kilohertz (kHz). aerial photographs with a scale of either 1:1,200 The transducers are horizontally spaced 90 degrees or 1:2,400. Aerial photographs at these scales apart on the transducer assembly; all transducers provided the detail necessary to show where have the same fixed angle from the vertical, re­ the boat transects followed the shoreline. The ferred to as a "beam angle," that is typically 20 aerial photographs were rectified and scaled by or 30 degrees. The transducer assembly may have recording, with the GPS receiver, the latitude and a convex or concave configuration. The pressure case is attached to the transducer assembly and longitude of at least four discrete points on each contains most of the instrument electronics. The photograph. Approximately 25 photographs were ADCP used for the bathymetric surveys of Morse required for each reservoir for complete coverage and Geist Reservoirs operates at a frequency of the shoreline. The most recent photographs of 600 kHz and has a transducer beam angle of available at the time of the study were taken in 20 degrees. March and April 1994. The 1994 aerial photo­ When an ADCP is deployed from a moving graphs identified changes to the shoreline from boat, it is connected by cable to a power source previous lake maps. Lake-level records indicate and to a portable laptop computer. The computer both reservoirs were close to normal pool is used to program the instrument, to monitor its elevation for most of March and April 1994. operation, and to collect and store the data.

Acoustic Doppler Current Profiler 5 ADCP transects/boat path GPS control point

Base from U.S. Geological Survey digital data,1:100,000 1983 Albers Equal Area projection standard parallels 29°30' and 45°30' central meridian -86°

Figure 2. Example of the pattern of boat paths used to collect bathymetry data with the acoustic Doppler current profiler (ADCP) and a global positioning system (GPS) on Geist Reservoir, central Indiana.

6 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 Components of typical ADCP cable connector /computer/power X cable laptop computer

pressure case ADCP mounted on a boat

transducer head transducer

I o o 2. (D O

(T> 3 o

3"| >j

Figure 3. Sketch showing the components of a typical acoustic Doppler current profiler (ADCP) and sketch of an ADCP mounted on a boat. The ADCP is capable of measuring velocity transducers must be fully submerged during magnitude and direction in the water column. In operation. The transducer draft is measured and bathymetric surveys of lakes, the depth and boat programmed into the ADCP as a depth-correction position, not the velocity of the water, are impor­ constant. "Blanking distance" refers to a zone tant (refer to Morlock, 1996, p. 9, for an explana­ directly below the transducers in which echoes tion of how the ADCP measures the velocity of cannot be received by the transducers because of water). their physical properties. "Lag" is the distance The ADCP computes boat speed and direction between successive parts of the pings transmitted using "bottom tracking" (RD Instruments, 1989). by an ADCP. The sum of the transducer draft, Measurement of the Doppler shift of acoustic blanking distance, and lag reduce the shallow- pulses reflected from the bottom determines water limit of operation. If the ADCP exceeds its the boat speed, and the ADCP on-board compass shallow-water limit, it will stop recording water determines the direction the boat is moving. The depth and bottom tracking; if the ADCP loses position of the boat is recorded as Northing and bottom tracking, it will not record new boat Easting, referenced from where the ADCP begins positions. With recent upgrades in technology, collecting data. The bottom-track echoes also are however, the ADCP has been operated success­ used to compute the depth of water. fully in water as shallow as 2 ft. As the boat moves along a transect, the Aquatic vegetation and irregularities in ADCP transmits acoustic pulses from its four the lake or channel bottom can affect the ADCP's transducers into the water column. The groups bottom-tracking capabilities. The ADCP is espe­ of pulses include water-profiling pulses (if pro­ cially sensitive to these factors in shallow water grammed) and bottom-tracking pulses. The ratio (3 ft or less). The ADCP continuously pings of water-profiling pulses (or water pings) to from all four transducers; however, it only needs bottom-tracking pulses (or bottom pings) can reflected signals at three transducers to maintain be set by the operator. This group of water pings bottom tracking. Bottom tracking will be lost if and bottom pings is called an "ensemble." For more than one transducer does not receive its bathymetry data, each ensemble includes an reflected signal. Irregularities in the bottom, such ensemble number, a transect position in Northing as chunks of rock, stumps, logs, or submerged and Easting, and four water depths one for each bridge abutments, can prevent reflected signals transducer. The four water depths, also referred from reaching the transducers. Lost bottom track­ to as "beam depths," are averaged for the average water depth of each ensemble. Because the trans­ ing can be detected by viewing the computer ducers have a fixed beam angle of 20 degrees monitor while data are being collected. If bottom pointing in four different directions, the average tracking is lost, the boat position will not be up­ water depth is representative of an area below the dated until bottom tracking is restored (at which ADCP rather than of a discrete point. This area point the Northing and Easting are updated from scanned below the ADCP will increase as water the last good ensemble). Lost bottom tracking is depth increases. not a serious problem if the boat is not moving; if the boat is moving when bottom tracking is lost, however, position errors can be propagated Operation Limitations through the rest of the transect. In such cases the transect should be terminated. ADCP's are subject to operation limita­ tions that directly affect their application to Other operation limitations can affect the bathymetry. One of these limitations is the inability quality of the bathymetry data. Boat speed and of an ADCP to collect data in shallow water, ADCP ping rate significantly can affect the preci­ which is also a limitation of conventional fathom­ sion of the resulting ensemble positions. The eters (depth finders). The inability of an ADCP ping rate is related to ADCP program parameters to collect data in shallow water is the result of (including the number of pings per ensemble and three factors: transducer draft, blanking distance, the time between pings) and the speed of the com­ and lag. "Transducer draft" refers to the depth that puter used to collect the data. The ratio of boat the transducers are submerged underwater; the speed to ADCP ping rate controls the amount of

8 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 sampling error in the boat-position data. If the boat is ±9 cm/sec (0.3 ft/sec) (RD Instruments, written speed is high and the ping rate is low, errors can commun., 1995). become significant. For quality-control purposes, water depths Pitching and rolling of an ADCP, such as were measured manually with a surveying rod when waves are present, also may affect measure­ at some of the GPS control points for comparison ment error. ADCP's have a pitch and roll sensor with water depths measured with the ADCP. that can be activated during data collection to Figure 4 shows a plot of the average water depth compensate for pitch and roll. The lakes were from the ADCP compared to the water depth from relatively calm for most of this study's bathymetry the surveying rod and a plot of the difference work, especially in bays; therefore, pitch and roll between the two depths versus the water depth compensation of the ADCP was not quantified. from the surveying rod. The mean difference between the two depths was +0.03 ft. This indi­ Accuracy of Acoustic Doppler cates the ADCP was unbiased in its measurement Current Profiler Methods of water depth because the overestimated values balance out the underestimated values, and the When configured for the bathymetry work average difference is close to zero. The standard described in this report, the ADCP measures water deviation of the differences between the two depth with an accuracy of ±10 centimeters (cm) methods was 0.29 ft, which is close to the ADCP or 0.33 ft; the accuracy of the bottom tracking manufacturer's estimated depth accuracy.

30 \.£. 1 ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ' ' I ' ' ' ' S 1.0

^25 z 0.8 -

gO.6 -

20 ^ 0.4 0- 8 0.2 " *^*t " I 0

£-0.2 * t Q 10 Z -0.4 * - 0 -0.6 z LJJ cc -0.8 - N = 41 LJJ LL Mean = -t-0.03 St -1.0 - Standard Deviation = 0.29 B Q .1 O . , . , i , , , , i , , , , i , . , , i , , , i i , , , , 5 10 15 20 25 30 0 5 10 15 20 25 30 WATER DEPTH FROM SURVEY ROD, IN FEET WATER DEPTH FROM SURVEY ROD, IN FEET

Figure 4. Comparison of (A) average water depth from the acoustic Doppler current profiler (ADCP) with water depth from a survey rod on Geist and Morse Reservoirs, central Indiana, and (B) a comparison of the difference in water depths between the two methods (ADCP-survey rod) and the water depth from a survey rod.

Accuracy of Acoustic Doppler Current Profiler Methods 9 Figure 4B shows that all but seven of the differ­ of Morse and Geist Reservoirs, the mobile GPS ences between the two methods are within ±0.3 ft receiver was programmed to not record positions of the measured depth. Some of the larger differ­ unless it was receiving signals from at least four ences shown in figure 4B can be explained by the satellites. Four satellites narrow the position to steep slopes where these depths were measured. a single point and cancel out time errors caused The steep slopes reduce the possibility that the bySA. average depth of the ADCP's four beams would The application of differential techniques match the surveying rod's point depth. provides the solution for obtaining higher GPS accuracy. Differential techniques use two receiv­ Global Positioning System ers a stationary base-station receiver at a known location and a mobile receiver in close proximity, The GPS equipment required for a bathy- within 500 kilometers (km), to the base station. metric survey includes a mobile GPS receiver Both receivers operate simultaneously. Two and a stationary (base-station) GPS receiver. receivers are used because each is influenced If real-time coordinate data are needed, the mobile almost equally by SA positional errors and by GPS receiver and the stationary receiver should atmosphere error. If the stationary receiver is be equipped with two-way communication de­ at a known location, it is possible to correct the vices; GPS coordinates then can be "differentially positional data collected by the mobile receiver corrected" (described in the following section) as by applying the amount of difference between the data are collected. the known location and the calculated location The GPS mobile receiver and base-station of the base-station receiver to the data collected receiver provide "real-world" coordinates for by the mobile receiver. the water-depth data recorded with the ADCP. Data can be corrected differentially at the Both receivers are needed to obtain the level of time they are collected or after they are collected. accuracy, 6.6-16.4 ft or 2 5 meters (m), required If the data are differentially corrected as they are to complete the surveys. Much of the following collected, real-time communication between the section, "Operation Principles," is based on Baker base station and the mobile receiver is required. and Morlock (1996). The differential corrections for this study were applied after the data were collected because real- Operation Principles time data were not required for the bathymetric surveys. The GPS receiver calculates its position Data collected for the lake surveys were on Earth by determining the distance from the differentially corrected with base-station files receiver to 3 or more of the 25 GPS satellites from the USGS Indiana District Office first-order orbiting the Earth. The position obtained by a base-station receiver. "First-order" means that the stand-alone GPS receiver is determined by location of the station is known with an accuracy "satellite trilateration." Satellite trilateration is of 1:100,000, or 3.9 in. (10 cm) over 6.2 mi the process of calculating the intersection of three (10 km). The station is centrally located and pro­ or more spheres, the centers of which are the posi­ vides sufficiently accurate base-station data for tions of the observable GPS satellites (Trimble most GPS data-collection efforts in Indiana. Navigation, 1994). Accuracy can be affected by the Department of Defense, which has the ability GPS data were collected for at least three to degrade GPS accuracy at any time with Selec­ control points along each ADCP transect, for each tive Availability (SA); the resulting absolute point depth measured with the surveying rod, and positional accuracy on the ground can be anywhere for each control point used to rectify and scale the between 25 and 100 m (Cloyd and others, 1995). aerial photographs. At least 120 position locations To improve accuracy for the bathymetric surveys were collected for most points. After the points

10 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 were differentially corrected, they were plotted and simultaneously with two GPS receivers located analyzed for "multipath errors." Multipath errors next to each other. The difference between the two occur when the GPS receives satellite signals positions was only 1.1 ft (0.33 m), which is reason­ reflected by an object (a tree or a cliff) before the able considering the GPS receivers are about 6 in. signal reaches the receiver. After multipath errors long and 3 in. wide. were eliminated, the remaining points were aver­ aged and a single longitude and latitude coordinate The analysis summarized in table 1 shows was obtained for each control point or data point. that the mobile GPS receiver with post-processed differential correction produces consistent results; Operation Limitations however, the analysis does not address the accu­ racy of the method to define a position in "real- The operation limitations of the GPS are world" coordinates. GPS positions were recorded Selective Availability (SA), multipath errors, and at known control points to determine the accuracy lost signals. As mentioned previously, SA is con­ of defining a position in "real-world" coordinates. trolled by the Department of Defense. Multipath Table 2 shows a comparison of six GPS readings errors can be reduced if the user selects sites in collected at known IMAGIS 1 control monuments relatively open areas and collects at least 120 in northwestern Marion County and northeastern position locations per site. Multipath errors become Hendricks County. Coordinates for these control obvious when the position locations are plotted; they then can be deleted before the position loca­ monuments were provided by the Marion County tions are averaged to compute a final position for Surveyor's Office. The average difference between each site. Lost signals are caused by obstacles the measured and known positions (latitude and between the mobile GPS receiver and the satellites longitude) was 9.29 ft (2.83 m) with a standard (tree canopy, buildings, hills, highway embank­ deviation of 4.98 ft (1.52 m). The average differ­ ments, bridges). Obstacles to satellite reception are ence in latitude was 12.6 ft (3.84 m), and the a particular problem in narrow arms of a reservoir average difference in longitude was 5.98 ft surrounded by tree-covered hills or buildings. Lost (1.82 m). These differences are consistent with signals also can occur during certain times of day the accuracy of the method (2 5 m) advertised when not enough satellites are available for the GPS receiver to read a position. by the manufacturer of the equipment used (Trimble Navigation, 1994). Operation limitations made it impractical to collect continuous GPS positions while running the ADCP transects. Using a few control points along each transect allows for the collection of GPS data BATHYMETRIC SURVEYS at any time, as long as the control points are fixed (such as a boat dock or an anchored buoy). The final data sets from the 1996 bathymetric surveys include ARC/INFO coverages for the Accuracy of Global Positioning shorelines, ADCP water-depth data, and shallow- water-depth data. Maps of Morse and Geist System Methods Reservoirs (figs. 5 and 6) show the distribution As mentioned previously, GPS control points of the ADCP and shallow-water-depth data. These often were used for more than one ADCP tran­ data were used to generate contour maps and to sect; this allowed an opportunity to check the compute volumes for Morse and Geist Reservoirs. reliability of the GPS positions. Redundant posi­ tions were recorded at several GPS control points that were revisited. Table 1 shows a comparison Indianapolis Mapping and Geographic Infrastructure of 10 sets of redundant GPS positions. The average System a consortium of private companies, public cor­ difference between the redundant pairs of GPS porations, city/county government units, and the Indiana University-Purdue University at Indianapolis. IMAGIS serves points was 3.1 ft (0.94 m). Table 1 also shows a as a geographically indexed data repository used for logistics, comparison between two different GPS receivers infrastructure development, and marketing planning (Richard used during the study to see if they produced dif­ Smith, Indianapolis Mapping and Geographic Infrastructure ferent results; points 070113A were collected System, written commun., 1996).

Bathymetric Surveys 11 Table 1. Comparison of redundant global positioning system (GPS) positions for evaluating the reproducibility of the GPS methods used to map Morse and Geist Reservoirs in central Indiana

Longitude Longitude1 Latitude Latitude2 Longitude difference difference Latitude difference difference GPS points (degrees) (degrees) (feet) (degrees) (degrees) (feet)

0509 15 A3 85.909472 39.952189 050923C 85.909455 0.000017 4.74 39.952192 0.000003 1.09 051315A 85.940452 39.931367 052 120 A 85.940445 .000007 1.95 39.931382 .000015 5.45 0521 ISA 85.953015 39.925192 0522 ISA 85.952999 .000016 4.47 39.925196 .000004 1.45 052 USA 85.953015 39.925192 0604 16K 85.952994 .000021 5.86 39.925173 .000019 6.90 0522 19E 85.976217 39.910703 0604 17C 85.976226 .000009 2.51 39.910696 .000007 2.54 0522 19F 85.982006 39.905745 0604 17A 85.982003 .000003 .84 39.905735 .000010 3.63 052220F 85.954941 39.930354 05302 IF 85.954923 .000018 5.02 39.930337 .000017 6.18

0701 13 A4 86.265496 39.875613 1.12 1.09 0701 13 A4 86.265492 .000004 39.875616 .000003 0709 14A 86.053925 40.076438 071021A 86.053934 .000009 2.51 40.076445 .000007 2.54 071115A 86.040212 40.090654 071221B 86.040218 .000006 1.67 40.090655 .000001 .36

AVERAGE 3.07 3.12

STANDARD DEVIATION 1.80 2.32

'Assumes that 1 second of longitude (.000278 degrees) is equal to 77.6 feet. 2Assumes that 1 second of latitude (.000278 degrees) is equal to 101 feet. 3Global positioning system points are labeled as month, day, hour, point. For example, 050915A is the first point collected after 15:00 hours Greenwich Mean Time on May 9, 1996. 4These two points were collected simultaneously with two different receivers placed side by side.

12 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 Table 2. Comparison of measured global positioning system (GPS) positions with known control points for evaluating the accuracy of the GPS methods used to map Morse and Geist Reservoirs in central Indiana [ °, degrees; ', minutes; ", seconds]

IMAGIS1 GPS-IMAGIS GPS-IMAGIS GPS control IMAGIS difference difference3 GPS point latitude/longitude monument latitude/longitude2 (seconds) (feet)

1004 14 A4 39° 51' 05.25382" 22 39° 51' 05.33178" -0.07796" 7.87 86° 17' 51.18841" 86° 17' 51.12467" 0.06374" 4.95

100416B 39° 54' 34.14567" 11 39° 54' 34.30390" -0.15823" 16.0 86° 20' 41.53233" 86° 20' 41.45635" 0.07598" 5.90

100417A 39° 51' 15.07208" 21 39° 51' 15.27621" -0.20413" 20.6 86° 11' 53.72758" 86° 11' 53.65621" 0.07137" 5.54

100418A 39° 53' 04.01030" 14 39° 53' 04.11678" -0.10648" 10.8 86° 12' 37.91960" 86° 12' 37.84732" 0.07228" 5.61

100418B 39° 55' 21.09169" 9 39° 55' 21.22668" -0.13499" 13.6 86° 13' 41.16376" 86° 13' 41.08756" 0.07620" 5.91

100419A 39° 54' 36.99899" 10 RESET 39° 54' 37.06586" -0.06687" 6.75 86° 16' 13.42553" 86° 16' 13.52802" -0.10249" 7.95

AVERAGE 9.29 STANDARD DEVIATION 4.98

'IMAGIS, Indianapolis Mapping and Geographic Infrastructure System a consortium of private companies, public corpora­ tions, city/county government units, and the Indiana University-Purdue University at Indianapolis. IMAGIS serves as a geographically indexed data repository used for logistics, infrastructure development, and marketing planning (Richard Smith, Indianapolis Mapping and Geographic Infrastructure System, written commun., 1996). 2Marion County Surveyor's Office, written commun., 1996. 3Assumes that 1" of latitude (.000278°) is equal to 101 feet, and l" of longitude (.000278°) is equal to 77.6 feet. 4Global positioning system points are labeled as month, day, hour, point. For example, 100414A is the first point collected after 14:00 hours Greenwich Mean Time on October 4, 1996.

Bathymetric Surveys 13 EXPLANATION

4=0 Cross section

ADCP transects/boat path

Shallow-water-depth point

1 Mile

0 0.25 0.5 1 Kilometer

Figure 5. Location of acoustic Doppler current profiler (ADCP) transects, shallow-water-depth points, and cross sections for Morse Reservoir, central Indiana.

14 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 EXPLANATION

Cross section

ADCP transects/boat path

Shallow-water-depth point

1 Mile

0 0.25 0.5 1 Kilometer

CD 0)

I

(D

Figure 6. Location of acoustic Doppler current profiler (ADCP) transects, shallow-water-depth points, and cross sections for Geist Reservoir, central Indiana. The volumes computed for the 1996 bathymetry ensure they did not differ by more than a few were compared to the volumes from the previous tenths of a foot (small variations were allowable bathymetric surveys to estimate the loss in reser­ because slight variations in locations of the four voir storage capacity because of sedimentation. beams would likely produce variations in the The following sections describe the contour map­ average depths). The ADCP transects also were ping, estimation of reservoir volumes, and the checked to ensure they passed through the GPS estimation of sedimentation. control points and did not cross the reservoir shoreline. The water-depth data were edited in areas Contour Mapping where depths of intersecting transects did not match. In areas where the transects crossed the Contour maps were generated for Morse and shoreline, either the transect data or the shoreline Geist Reservoirs by use of ARC/INFO. ADCP data were edited. Most edits involved adjusting water-depth and location data and GPS coordinates the position of the transect or shoreline slightly. were processed and converted to ARC/INFO If errors in position seemed excessive, all or parts coverages. Coverages for the shorelines, ADCP of the transect were deleted. Position errors in water-depth data, and the shallow-water-depth water-depth data were attributed to errors in the data were used to generate the maps. bottom-tracking caused by inaccuracies of the on-board compass of the ADCP; the analysis of Contour Map Generation the accuracy of the GPS methods indicated that positions on average could be determined within The first step in creating contour maps was to 10 ft. Some of the initial depth data collected transfer all data collected with the ADCP and GPS from Morse and Geist Reservoirs had significant receivers to the ARC/INFO data base. The ADCP position errors caused by excessive boat speed manufacturer's data-processing software was used (5 knots maximum) coupled with a slow ADCP to produce text files of all data sets collected with ping rate. Data were re-collected where needed the ADCP. One text file was created for each with a faster ADCP ping rate and with a slower ADCP transect. The data from the GPS receivers boat speed (3 knots maximum). After data editing, were processed with software provided by the GPS all transects were appended within ARC/INFO manufacturer. Text strings containing latitude and to create master depth coverages that included all longitude were produced for all control points. The ADCP depth data for each reservoir. The master ADCP and GPS text files were used to generate depth coverages also included the point depths ARC/INFO coverages. All coverages were con­ collected by manual soundings in shallow areas. verted into a map projection for making contour The coverages of shorelines and water-depth maps. The Universal Transverse Mercator (UTM) data were used to generate contour maps and projection was selected because it is commonly to compute reservoir volumes. Two different used for the scale of maps to be created. ARC/INFO software methods of surface genera­ Data in the ARC/INFO water-depth coverages tion for contouring TIN and Topogrid were were edited to identify and delete points with one used and evaluated. or more invalid ADCP beam depth (for this discus­ The acronym TIN stands for Triangulated sion, the term "point" refers to a single ADCP Irregular Network (Environmental Systems ensemble and position; each point has four Research Institute, Inc., 1991) and is defined as: ADCP beam depths). After invalid data points ... a set of adjacent, non-overlapping were removed from the coverages, average triangles computed from irregularly depths were computed from the four ADCP spaced points with x, y coordinates beam depths and corrected for normal pool and z values. The TIN model stores elevation. the topological relationship between All water-depth data were quality checked triangles and their adjacent neighbors; by an inspection of the average ADCP beam i.e., which points define each triangle depths at intersecting transects. The beam depths and which triangles are adjacent to of each transect were checked at intersections to each other.

16 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 For the water-depth coverages, the x, y coor­ Contour Mapping Limitations dinates are UTM coordinates and the z values are water depth in feet. The TIN model subdivides the It would not have been practical to develop bathymetric data of the reservoir into thousands hand-drawn contour maps for Geist and Morse of triangles. Each of these triangles or UN's has a Reservoirs because more than 120,000 data points surface area and an average depth. The ARC/INFO were used to produce each map. ARC/INFO was command "TINcontour" generates contours using capable of generating contours from the data, but the process had limitations. One obvious limitation the TIN surface. Refer to the ARC/INO docu­ was that the computer-generated contours were not mentation for a detailed discussion of TIN and as aesthetically pleasing as hand-drawn contours. TINcontour (Environmental Systems Research This problem can be minimal if data are collected Institute, Inc., 1991). in a grid pattern dense enough to identify all ESRI states that Topogrid generates a "hydro- features, including linear features such as stream logically correct" grid of elevation (Environmental channels. Many of the 120,000 data points used Systems Research Institute, Inc., 1994). In the case for contouring each reservoir were packed tightly of a reservoir, for example, the submerged stream along transects, resulting in many duplicate data channel might be defined by a limited number of points. Ideally, data would be distributed in a uniform grid for computer contouring; however, data points. Topogrid could generate a smooth, it may be impractical and inefficient to collect data continuous stream-channel surface from the points in this manner on large reservoirs. (the shape and continuity of the surface is dictated by factors such as data density and location). The Most of the limitations in producing contour ARC/INFO command "Latticegrid" was used to maps with methods described in this report were generate water-depth contours from the Topogrid related to data collection. In some areas, the data coverage was not adequate to properly define surfaces. topographic features, especially stream channels. Contour map surfaces generated from the Inadequate data resulted in missing contours; TIN and Topogrid methods were evaluated by a contours in the wrong positions; or contours that comparison of the contours with selected point defined isolated "islands" when they should depths. Inaccuracies in the Topogrid-generated have defined continuous, linear features such as contours resulted in selection of the TIN-generated submerged stream channels. In some areas, depths contours for the contour maps. Limitations in the were collected near the shoreline then collected use of TIN and Topogrid for this project are dis­ at a considerable distance from the shore (figs. 5 cussed in the "Contour Mapping Limitations" and 6). This had the effect of "pulling" some depth section. contours away from their true position and out towards the next closest data point, causing the The TIN-generated contours were examined contour lines to define protrusions into the reser­ and required manual edits in some areas. Most voir that were not real. edits consisted of manually smoothing contour Some limitations are associated with TIN and lines and connecting isolated closures in contour Topogrid, but these limitations apply specifically lines, for example, to follow a known submerged to this project. Changes in software configurations channel or roadbed. The Topogrid surface pro­ and data-collection techniques could change or duced smoother contour lines than the TIN eliminate the limitations discussed below. surface and was used as a guide to smooth the The locations and shapes of contours gener­ TIN-generated contour lines. Older contour maps ated from the TIN surfaces were accurate where of the reservoirs also were used to identify areas depth data were sufficient. TINcontour produces on the TIN-generated map that could be edited, straight and angular contour lines, which are not as especially along the submerged stream channels. aesthetically pleasing as hand-drawn contour lines. Completing the edits to the TIN-generated con­ Because contour lines are generally smooth, the tours produced the final contour maps for Morse angularity of TIN contours appeared unrealistic in and Geist Reservoirs (figs. 7 and 8). some areas and needed to be smoothed manually.

Contour Mapping 17 86°04' 86°01' I

EXPLANATION Contours Show depth below water level at normal pool elevation (810 feet above sea level). Contour interval is 5 feet

40°08'

0.25 0.5 1 MILE I

40°04'30" 0 0.25 0.5 1 KILOMETER

Universal Transverse Mercator projection Zone 16

Figure 7. Water-depth contours of Morse Reservoir, central Indiana. EXPLANATION

Contours Show depth below water level at normal pool elevation (785 feet above sea level). Contour interval is 5 feet

39°56'50" _

39°55' -

Universal Transverse Mercator projection Zone 16

Figure 8. Water-depth contours of Geist Reservoir, central Indiana Part of the problem with contours protruding from that volumes would not be underestimated from shore was a function of the TINcontour procedure. shallow contour lines inaccurately extending into The protrusion of contour lines into areas of deeper areas of deeper water. water was edited, and data points were added to Computations of volume by TIN may be influ­ the coverage to represent where the contour lines enced by the density of data because TIN sums should be located. This editing was done before the volumes of areas of equal depth. Greater densities volume calculations (discussed in the next section) of data are likely to increase accuracy; for exam­ were made to ensure that the volumes would not be ple, increasing the data collected in a channel area underestimated. might result in more areas of greater average depth, thereby increasing the computed volume. This In some areas, the Topogrid-generated project did not attempt to quantify the effect on contours appeared more representative of real volume computations with varying data density. topographic features than the TIN-generated contours. ESRI states that Topogrid is designed to produce "hydrologically correct" surfaces Morse Reservoir (Environmental Systems Research Institute, Inc., 1994). In many areas, Topogrid contour lines were The volume of Morse Reservoir based on not as accurate as desired, probably because Topo­ the 1996 bathymetry is 22,820 acre-ft (7.44 Bgal). The surface area of the reservoir (not including grid computes grid values by averaging only four islands) was computed to be 1,484 acres, making data points. For example, shallow contours would the average depth of water 15.4 ft. In much of extend into areas that were known to be deep. The the north end of the reservoir and at the mouths inaccuracies may have been reduced or eliminated of tributaries, the water is less than 5 ft deep; in by reducing the grid size of the Topogrid surface. many areas at the south end of the reservoir, water It was beyond the scope of this project to depths of 40 ft or more were measured in the sub­ analyze the many programs/algorithms available merged channel of Cicero Creek (fig. 7). for computer contouring. It is possible that some other method would produce a more accurate Geist Reservoir computer-generated map with the available data and not require manual editing. With the manual The volume of Geist Reservoir based on the editing, the TIN-generated contours (figs. 7 and 8) 1996 bathymetry is 19,280 acre-ft (6.29 Bgal). are accurate representations of the reservoir The surface area of the reservoir (not including bathymetries but could be improved with addi­ islands) was computed to be 1,848 acres, making tional data. The data coverages shown in figures 5 the average depth of water 10.4 ft. In much of the and 6 can be used to evaluate the contour maps upper end of the reservoir and at the mouths of the denser the data coverage, the more accurate tributaries, the water is less than 5 ft deep; in a few the contours. areas at the lower end of the reservoir, water depths of 25 ft or more were measured in the submerged channel of Fall Creek (fig. 8). The 1996 volume Estimation of Reservoir Volumes and area include the addition of several bays and inlets that did not exist in 1980. The two largest of the new bays were apparently old sand and In addition to creating water-depth contours, gravel quarries and had a combined area of the TIN-generated surface was used to compute about 38 acres and a combined volume of about volumes for both reservoirs. Each triangle gener­ 523 acre-ft (170.4 Mgal). ated by TIN has a surface area and an average depth, the product of which is volume. The sum of all of the TIN volumes is the volume of the Estimation of Sedimentation reservoir. The final TIN-generated surface was computed after data points were added to represent Reductions in reservoir storage capacity from the edited locations of contour lines, as explained the design volumes and since the previous bathy- in the previous section. This editing was done so metric surveys can be attributed to sedimentation.

20 Bathymetric Surveys, Morse and Gelst Reservoirs, Central Indiana, 1996 The lost storage capacity, or volume of sediment, Morse Reservoir has more relief and a more was estimated by subtracting the 1996 reservoir defined channel than Geist Reservoir. Therefore, volumes from the previous estimates of volumes. the volume estimates for Morse Reservoir may Before the differences could be estimated, how­ be less accurate than those for Geist Reservoir. ever, the 1996 shorelines had to be adjusted to match the shorelines from the previous bathymetric surveys (Morse Reservoir in 1978 and Geist Reser­ Morse Reservoir voir in 1980). Contour maps provided by the IWC Bakken and Bruns (1991) reported an and old aerial photographs indicated the shorelines original (1956) design volume of 25,380 acre-ft changed since the last surveys. The shoreline of Geist Reservoir has undergone the most change (8.27 Bgal) for Morse Reservoir and a 1978 vol­ with the addition of two new bays that were appar­ ume of 22,100 acre-ft (7.2 Bgal). This difference ently old sand and gravel quarries and the addition represents a 12.9-percent reduction in reservoir of some smaller bays for boat docking. The 1996 volume over 22 years. The 1996 volume with the shorelines were adjusted by deleting features that 1978 shoreline was computed to be 22,810 acre-ft did not exist at the time of the earlier surveys and (7.44 Bgal), which is 3.2 percent larger than the by generally trying to match the 1996 shorelines volume computed for 1978. The area of the reser­ to those represented on the maps provided by voir, adjusted to represent the 1978 shoreline, the IWC. was 1,508 acres. The comparison of 1996 reservoir volumes The difference in volume can be attributed to with previous volumes should be considered the different methods used to compute volume and gross estimates because the volumes were com­ not to an actual increase in volume. The volume of puted with different methods. The 1996 volumes 22,810 acre-ft represents a 10.1-percent reduction are computer generated (TIN), based on the from the design volume (since 1956); however, bathymetry data that were collected throughout the design volume probably was estimated with the reservoirs (figs. 5 and 6). Although the density the cross-section area method. The 1996 volumes, of data varies, most areas of the reservoirs were either with the 1978 shoreline (22,810 acre-ft) or covered. The 1978 volume for Morse Reservoir the 1996 shoreline (22,820 acre-ft), are smaller was based on a network of 25 cross sections than the design volume (25,380 acre-ft), which (fathometer profiles), and the 1980 volume for suggests sedimentation is reducing the storage Geist Reservoir was based on a network of 40 cross capacity of Morse Reservoir. Because different sections (fathometer profiles). Reservoir volumes methods were used to compute volume, the actual were calculated by measuring the area of the loss in storage capacity and the annual sedimenta­ cross sections and applying the areas to lengths of tion rate cannot be estimated. reservoir between the cross sections (Steve Grant, Indianapolis Water Company, personal commun., Figures 9 through 19 (Supplemental Data at 1997). The design volumes probably were based back of report) are comparisons of the 1978 fath­ on valley sections of the topographical surveys ometer profiles from a sedimentation project to the prior to construction of the reservoirs. cross sections generated from the TIN computed The computer-generated (TIN) volumes for for the 1996 bathymetry. The locations of the cross the 1996 bathymetry are based on a more accurate sections are shown in figure 5; the numbers of method that uses data for the entire reservoir and the cross sections are the same as those used in the not just data from along a few cross sections. The IWC sedimentation project. A representative sam­ accuracy of the TIN may be affected by the density ple of the 25 IWC cross sections was selected to of the data coverage. Ideally, data should be col­ show sedimentation and changes in the reservoir lected in a grid pattern dense enough to allow the bottom. The depth of water in figures 9 through 19 TIN to identify all of the bottom features. This may is referenced to a normal pool elevation of 810 ft not be practical, however, on large reservoirs. above sea level.

Estimation of Sedimentation 21 The cross sections are viewed in the down­ Geist Reservoir stream direction, with the horizontal station referenced to zero at the left end. Differences in Bakken and Bruns (1991) reported an the lengths of the cross sections and positions of original (1943) design volume of 21,180 acre-ft bottom features could be caused by discrepancies (6.9 Bgal) for Geist Reservoir and a 1980 volume of 18,720 acre-ft (6.1 Bgal). The difference repre­ in the shorelines used for the two studies and the sents an 11.6-percent reduction in reservoir volume technique used to measure the horizontal station over 37 years. The 1996 volume, computed with along the fathometer profiles. The 1996 cross the 1980 shoreline, was 18,630 acre-ft (6.08 Bgal) sections are computer generated from a TIN of and represents a 0.4-percent reduction in reservoir the bathymetry. The depth of water was computed volume since 1980 and a 12.0-percent reduction every meter (3.281 ft) along the sections, from since 1943. The area of the reservoir, adjusted to the left edge of water to the right edge of water. represent the 1980 shoreline, was 1,756 acres. The lengths of the 1996 cross sections are based The estimated reduction in reservoir volume on the shoreline coverages made from aerial of 0.4 percent from 1980 to 1996 is not consis­ photographs. tent with the estimated reduction in volume of The cross sections were selected to show 11.6 percent for the 37 years prior to 1980. This inconsistency can be attributed to the different potential changes in the bottom of the reservoir, method used to estimate the 1996 volume than that from the dam (fig. 9) to the headwaters where used for the previous estimates by the IWC. Dredg­ Cicero Creek flows into the reservoir (fig. 19). ing also could contribute to this small difference. All of the cross sections indicate some sedimenta­ Some places appear to have been dredged to allow tion has occurred, but because of the limitations boat traffic around docks, but it is not known if of the data present and past the sedimentation dredging did occur and if the dredged sediments cannot be quantified accurately. The sedimentation were removed from the reservoir. appears less in the lower parts of the reservoir near Cross sections were generated for the 1996 the dam. In these areas, the sedimentation appears bathymetry and compared to the 1980 data to show to have occured mainly in and near the submerged if sedimentation has occured in Geist Reservoir stream channel. Cross sections in the headwater since 1980. Figures 20 through 31 (Supplemental areas show as much as 1 ft of sedimentation in Data at back of report) are comparisons of the 1980 some areas. fathometer profiles from a sedimentation project to the cross sections generated from the TIN com­ Some of the discrepancies between the 1996 puted for the 1996 bathymetry. The locations of the cross sections and the 1978 fathometer profiles cross sections are shown in figure 6; the numbers were caused by natural processes in the reservoir, of the cross sections are the same as those used by such as sedimentation. Some discrepancies most the 1980 IWC sedimentation project. A represen­ likely were caused by areas of sparse data collec­ tative sample of the 40 IWC cross sections was tion, particularly in and near the submerged stream selected to show sedimentation and changes in the channel. The accuracy of the water depths for reservoir bottom. The depth of water in figures 20 through 31 is referenced to a normal pool elevation the cross sections is based on the proximity of the of 785 ft above sea level. cross section to bathymetry data. Intersections of the cross sections and the ADCP transects are The 1996 cross sections for Geist Reservoir shown on figures 9 through 19 (at back of report). were generated with the same method as those for Morse Reservoir. The cross sections were selected Cross sections that parallel ADCP transects also to show potential changes in the bottom of the will show a more accurate representation of the reservoir, from the dam (fig. 20) to the headwaters water depths than areas not near a transect (fig. 5). where Fall Creek flows into the reservoir (fig. 31). The proximity of a cross section to the bathymetry As with Morse Reservoir, the accuracy of the cross data should be considered when evaluating the sections is related to the proximity of the cross cross sections for sedimentation. section to the bathymetry data. Figures 20

22 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 through 31 (at back of report) show where the cross of a shoreline and water depths with positions in sections intersect ADCP transects. Some of the a Universal Transverse Mercator projection. These cross sections also parallel ADCP transects for coverages were used by the GIS to generate limited distances (fig. 6). contour maps and to compute volumes for each All of the cross sections indicate sedimenta­ reservoir. Because the computer-contouring meth­ tion, which suggests that the estimated reduction ods had limitations, the final contour maps were in volume of 0.4 percent from 1980 to 1996 under­ edited manually to smooth and connect areas of estimates the amount of sedimentation. Many of closure that were determined to be continuous (for the cross sections show areas with at least 1 ft example, a submerged stream channel or roadbed). of sedimentation. If 1 ft of sediment were added Reservoir volumes were computed with to the entire bottom of the reservoir (1,848 acres), the GIS by generating a surface for the 1996 a reduction of 8.7 percent from the design volume bathymetry. The 1996 area and volume of Morse of 21,180 acre-ft would result. Because of the Reservoir were computed to be 1,484 acres and limitations of the data present and past 22,820 acre-ft (7.44 Bgal), respectively. The 1996 the sedimentation, however, cannot be quantified area and volume of Geist Reservoir were computed accurately. to be 1,848 acres and 19,280 acre-ft (6.29 Bgal), Accurate estimates of the reduction in respectively. reservoir volume since 1980 and the annual sedi­ The reservoir volumes from 1996 were com­ mentation rate cannot be made because the 1980 pared to previous reservoir volumes to estimate and 1996 volumes were computed with different the reduction in storage capacity resulting from methods. Figures 20 through 31 (at back of report), sedimentation. Previous reservoir volumes in­ however, suggest that 0.4 percent underestimates cluded the design volumes for each reservoir and the reduction of volume in Geist Reservoir since volumes resulting from sedimentation projects 1980. The 1996 volumes, either with the 1980 on Morse Reservoir in 1978 and Geist Reservoir shoreline (18,630 acre-ft) or the 1996 shoreline in 1980. Because different methods were used (19,280 acre-ft), are smaller than the design to compute volume, the actual loss in storage volume (21,180 acre-ft); this difference suggests capacity and the annual sedimentation rate could sedimentation is reducing the storage capacity of not be estimated. The 1996 volumes were from a Geist Reservoir. computer-generated surface based on data spread throughout the reservoirs. The volumes from the earlier sedimentation projects were estimated from SUMMARY AND CONCLUSIONS a network of fathometer profiles on each reservoir. Design volumes probably were based on cross Morse and Geist Reservoirs are large artificial sections of the topographical surveys of the valleys lakes in central Indiana that are used primarily prior to construction of the reservoirs. To verify for public water supply. The bathymetry of the sedimentation, cross sections were constructed reservoirs was mapped from April 1996 through from the computer-generated surfaces for 1996 October 1996 by use of an acoustic Doppler cur­ and compared to the fathometer profiles from the rent profiler (ADCP) and a global positioning 1978 and 1980 sedimentation projects. These cross system (GPS) mobile receiver. The ADCP was sections indicate some sedimentation throughout used to measure water depth and position from both reservoirs. a boat, and the GPS receiver was used to collect One of the objectives of this report was to positions in latitude and longitude at control points evaluate the use of ADCP and GPS technology for along the boat path to convert ADCP coordinates bathymetric surveys. Bathymetric mapping of large to "real-world" coordinates. lakes with the technologies and methods described The ADCP and GPS data were post-processed in this report is practical. More than 120,000 data and imported to a geographic information system points were collected on each reservoir. The ADCP (GIS). The water depth and position data were and GPS technology eliminated the need to string processed with the GIS to produce a data base, or tag lines across the lake or to determine the boat coverage, for each reservoir. Coverages consisted position from shore-based instruments, allowing

Summary and Conclusions 23 more bathymetric data to be collected in less time Bakken, J.D. and Bruns, T.M., 1991, Assessing the and with less manpower than with conventional reliability of urban reservoir supplies: Journal of methods. One boat crew collected the data on each American Water Works Association, v. 83, no. 3, reservoir in less than 20 (non-consecutive) field p. 46-51. days. The accuracy of the computer-generated Cloyd, P., Gray, E.R., and van Gelder, B.H.W., 1995, contour maps and reservoir volumes, however, Status of the Proposed Federal/Cooperative Base could be increased if additional data were collected Network (FBN/CBN) for the State of Indiana: to define local features in the bathymetry. Morse School of Civil Engineering, Purdue University, Reservoir has a more defined channel and more West Lafayette, Ind., 15 p. relief compared to Geist Reservoir and, therefore, Environmental Systems Research Institute, Inc., 1991, should require more data to accurately map such ARC/INFO user's guide, surface modeling with features. TIN, surface analysis and display: July 1991, An understanding of the limitations of the [variously paged]. technology used in this study can be helpful. The .1994, Coverage definition, Topogrid command ADCP has a shallow-water limit of about 2 ft and, references, ARC/INFO Version 7.0.4 ArcDoc, when operated in depths less than 3 ft, is affected Redlands, Calif, [On-line documentation]. by irregularities in the bottom such as vegetation, Indiana Department of Natural Resources, 1994, Water rocks, and logs. Also, the configuration of the resource availability in the Lake Michigan Region: ADCP and the speed of the boat can affect the data Indianapolis, Ind., 1994, p. 1-2. quality. GPS receivers will not work in locations Hoggatt, R.E., 1975, Drainage areas of Indiana streams: where tree canopies, buildings, and road embank­ U.S. Geological Survey, 231 p. ments block satellite signals. Morlock, S.E., 1996, Evaluation of acoustic Doppler current profiler measurements of river discharge: U.S. Geological Survey Water-Resources Investi­ REFERENCES CITED gations Report 95-4218, 37 p. Baker, N.T., and Morlock, S.E., 1996, Use of a global RD Instruments, 1989, Acoustic Doppler current positioning system and an acoustic Doppler current profilers, principles of operation A practical profiler to map river and lake bathymetry, in primer: San Diego, Calif., RD Instruments, 36 p. Hallam, C.A., Salisbury, J.M., Lanfear, K.J., and Trimble Navigation, 1994, GPS Mapping Systems, Battaglin, W.A., eds., Proceedings of the AWRA General Reference Trimble Navigation Limited, Annual Symposium, GIS and Water Resources: Surveying and Mapping Division GeoExplorer American Water Resources Association, Herndon, Software and Manuals PN 24177-00: Trimble Va., TPS-96-3, p. 373-381. Navigation, Sunnyvale, Calif.

24 Bathymetric Surveys, Morse and Geist Reservoirs, Central Indiana, 1996 SUPPLEMENTAL DATA CROSS SECTIONS OF MORSE RESERVOIR CD 0) < NW Morse Reservoir #2 SE o 815 0) i 810

805 LU 0) o. h- 10 800 y o LU LU LU 795 0) 31 LU (A > ULJ 20 790 § I W O 25 785 LU UL LU 3 O LL I 5" 30 780 Z~ O 5'Q. t LU 0) 35 775

(O (O o> 40 770

45 - 1996 Bathymetry 765 ° Intersection with bathymetry transect Vertical exaggeration x 20 50 760 200 400 600 800 1,000 1,200 1,400 1,600 1,800 HORIZONTAL STATION, IN FEET

Figure 9. Cross section #2 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. NE Morse Reservoir #3 sw 815

810

805

800 2 CO

795 § <

UJ 790 LU

785 O !c

30 780 UJ o 1978 Fathometer profile 8 35 775 w - 1996 Bathymetry ° Intersection with bathymetry transect Vertical exaggeration x 20 40 ._____i_____-_____i ____I_____. 770 200 400 600 800 1,000 1,200 HORIZONTAL STATION, IN FEET

Figure 10. Cross section #3 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation 30 (D project) and a cross section from the bathymetric surface computed from the 1996 survey. CO fit I

NW Morse Reservoir SE

OI3 §

Q. 0 <- 9 - 810 LU V j CA LU 33 LU LU v^ ,_ // i < ** ». ""'*'>w ' / LU 5 _ "*>-».^> ^>s>>. J i _ 805 C/3 2 ^^^x^^ / / LU of ""* * ^H^». _/ / § O LU ^"^ -^^ ^-*s CD (D \- < 10 - 800 < \- > LU U_ LU LL 5'Q. O ; ; i 15 _ 795 2 ^ . O «o LU 8 O - 1 79O LUJ 20 1978 Fathometer profile f 9w _J _ LU . 1996 Bathymetry Vertical exaggeration x 20 ° Intersection with bathymetry transect 95 i . i . i . i i i 785 200 400 600 800 1,000 1,100 HORIZONTAL STATION, IN FEET

Figure 11. Cross section #5 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. Morse Reservoir #6 NW 815

810

805

800

795

790

785

780

775

770

1978 Fathometer profile 765 1996 Bathymetry 760 Vertical exaggeration x 20 Intersection with bathymetry transect o w __,___i___,___i___. w 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2.JS* IT HORIZONTAL STATION, IN FEET

Figure 12. Cross section #6 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. SE Morse Reservoir #8 NW 2. ^ o' 815 W I

30 A (A A i

O A

HI 1978 Fathometer profile 1996 Bathymetry Intersection with bathymetry transect i , _ i 770 200 400 600 800 1,000 1,200 1,400 1,600 HORIZONTAL STATION, IN FEET

Figure 13. Cross section #8 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. Morse Reservoir #10 w 815

1978 Fathometer profile - 1996 Bathymetry o 5 Intersection with bathymetry transect (A 770 (A 200 400 600 800 1,000 1,200 1,400 1,600 HORIZONTAL STATION, IN FEET

Figure 14. Cross section #10 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. CO to

2. o"^ 0) NE Morse Reservoir #1 2 sw 820

815

0) 810 -I Q. LU s 805 HI (O 33 800 jjj to 795 m O 790 CO

785 [j] HI 780 Q.5' 3 0) 775 O to 770 I 1978 Fathometer profile 765 LU 1996 Bathymetry 1 Vertical exaggeration x 20 760 ° Intersection with bathymetry transect 755 500 1,000 1,500 2,000 2,500 2,800 HORIZONTAL STATION, IN FEET

Figure 15. Cross section #12 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. NE Morse Reservoir #14 sw

,.,. i .,.,,,., O£U

_ _ 815 _J HI : ; 1- 0< I" O i 810 &Ij HI HI LL \ / / : 5 \ 1 1 CO ? 5 805 LU of § HI ;K / CD < 10 800 < £ \ \ / / - ID LL \ \ ' / HI \ \ t / ' LL

^F° 15 795 . Z : VX Vs^ --» ^9- -Oo - """' ^/y ~ Q. o LJJ . i_ Q 20 - 790 < HI ^^^ " 1 978 Fathometer profile HI 25 785 .._,., .. __ - 1996 Bathymetry Vertical exaggeration x20 ' , ° Intersection with bathymetry transect 30 i i i i i i i . i i i i i " Tfln 0 200 400 600 800 1,000 1,200 1,400 1,500~ HORIZONTAL STATION, IN FEET

o Figure 16. Cross section #14 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. 00 0) o o' iCO SE Morse Reservoir #1 6 NW ; i | i i i | i | i i i | i | i | i | . - BZU (D 0) -I O. 815 O LLJ (D h- 0< P~ 810 [j \ / / - J LLJ LLJ c * 1 ' ' LL 5 805 LLJ [\ I j ; CO Z LLJ of 10 800 > O LLJ ~^=^ sfJ ' CD < 15 795 ^ ^~^L-s LLJ II LLJ Q.5* o 20 ~ ~ 790 LL z" 0) I . £L 25 - 785 O (D ! \ LLJ 8 G ^ 30 _ _ 780 > ^~B^~ * i9/o i auioiTioisr prunio LLJ _J .. .. , .. _.. - 1996 Bathymetry LLJ 35 Vertical exaggeration x 20 ~ 775 ° Intersection with bathymetry transect '. Art i , i , i . i i i . i . i . i . i , 77O 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 HORIZONTAL STATION, IN FEET

Figure 17. Cross section #16 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. SE Morse Reservoir #18 NW 820

815 _ 111 810 LLJ LLJ LU 0) £ 5 805 HI CC § 111 CD 10 800 I LL LU LL O 15 795 I Q_ LU Q 20 790 < LU 1978 Fathometer profile LU 25 785 1996 Bathymetry o Vertical exaggeration x 20 i Intersection with bathymetry transect (0 30 780 200 400 600 800 1,000 1,200 1,400 1,500 HORIZONTAL STATION, IN FEET Io a(0 o Figure 18. Cross section #18 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. CD u

815 HI

HI HI 810 s CO * HI CC 5 805 O UJ CD .11 _ ____ O -- / I- Q

20 790 QJ : Vertical exaggeration x 20 ' 1"6 Bathymetry - . ° Intersection with bathymetry transect ' 9fi 1,1,1.1,1,1 7B5 200 400 600 800 1,000 1,200 1,300 HORIZONTAL STATION, IN FEET

Figure 19. Cross section #20 of Morse Reservoir, central Indiana, from a 1978 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. SUPPLEMENTAL DATA CROSS SECTIONS OF GEIST RESERVOIR CD tt «<5

Geist Reservoir #1 NW (A (B 790 0) Q. O 785 (B 5T 3) (B 780 CO 775 O O (B CQ 770

3 5'Q. LJJ 765 U_ 0)

<£> O <£> at 760 1980 Fathometer profile

- 1996 Bathymetry 755 ILJJ Vertical exaggeration x 20 ° Intersection with bathymetry transect 750 200 400 600 800 1,000 1,200 1,400 1,600 1,800 HORIZONTAL STATION, IN FEET

Figure 20. Cross section #1 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. SE Geist Reservoir #7 NW 790

1980 Fathometer profile

1996 Bathymetry O Intersection with bathymetry transect

745 I 200 400 600 800 1,000 1,200 1.400 1,600 1,800 2,000 5 HORIZONTAL STATION, IN FEET v> 2. 8

3d Figure 21. Cross section #7 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) (D g and a cross section from the bathymetric surface computed from the 1996 survey. O toCO DO

s SE Geist Reservoir #8 NW 790

0) Q. O 785 Qj (D S 30 (D UJ $ UJ 5 780 i LU o 775 O (D CO

fc 15 770 UJ Q. LJL

Q. 20 "I UJ Q 1980 Fathometer profile UJ 25 760 Q-j - 1996 Bathymetry Vertical exaggeration x 20 ° Intersection with bathymetry transect 30 _____I_____i I 755 200 400 600 800 1,000 1,200 1,300 HORIZONTAL STATION, IN FEET

Figure 22. Cross section #8 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. SE Geist Reservoir #12 NW 790

UJ

785 UJ

UJ 0) UJ 780 > CO

775 o

770 1980 Fathometer profile ^ UJ g 1996 Bathymetry o UJ Cft Intersection with bathymetry transect (0 765 200 400 600 800 1,000 o HORIZONTAL STATION, IN FEET (A o O 25'(V a Figure 23. Cross section #12 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. CD

01 a O (D

O. to to

1980 Fathometer profile

1996 Bathymetry LU ° Intersection with bathymetry transect 760 200 400 600 800 1,000 1,200 1,400 1,600 HORIZONTAL STATION, IN FEET

Figure 24. Cross section #15 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. Geist Reservoir #20 N i .... , ....,....,.,..,.... /»o _J _ _ 790 LLI > h- 0< ___ o 785 _| LLI ^^N^ ^*"**» J LLI LL. 5 ^^ ^.^ -"^X3v / 780 HI ^^^^^^^^^ / CO Z~~ 10 775 £ of N^ /-, / O £ 15 ^^**^^ ^S ' N^- ~^_ ^ar^ 770 CO £3 ^~ ^ 20 765 t LL. LLI O 25 - 760 LL.z" I t" 30 _ 755 O Q. LLI ^^^^ M 1i9ou QAD FstHnnmCktori auiuiTimvf nrrtfiloprunio Q 35 750 < o - 1996 Bathymetry LJJ 40 Vertical exaggeration x2D - 745 _l ° Intersection with bathymetry transect \ LLI I ._ , . . . i , , , . i . . . . i . . . . i . . . . i . . . . - 7AT\ 0 500 1,000 1,500 2,000 2,500 3,000*" I HORIZONTAL STATION, IN FEET § o i CO i Figure 25. Cross section #20 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. oi & 00

I

a.3 Geist Reservoir #26 N O 795 9

Q.

1980 Fathometer profile 1996 Bathymetry Intersection with bathymetry transect HI 735 500 1,000 1,500 2,000 2,500 3,000 3,200 HORIZONTAL STATION, IN FEET

Figure 26. Cross section #26 of Morse Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. SE Geist Reservoir #29 NW i | | i | i | | | , | i | i | , | /»o

- 790 UJ '- I- o< 785 -J UJ UJ \r*~* t 1 1 ^^ ^^tm, ¥ "- 5 78003 ~ ^^^ ~~ ^"^N. X- /$ z UJ of 10 : ^ />^^-~-----'- - 775 § UJ CD < 15 770 < £ b U- 20 !_ _ 765 UJ O LL £ 25 - : 760 § ol Q 30 1980 Fathometer profile 755 < 1996 Bathymetry '. UJ o 35 0 Vertical exaggeration x20 ~ 750 si ° Intersection with bathymetry transect ; 7AK Art i , i , i . i . i . i . i . i . i . i . i . ft 0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400~ o' HORIZONTAL STATION, IN FEET 3 o

(0i 3) Figure 27. Cross section #29 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation (D » project) and a cross section from the bathymetric surface computed from the 1996 survey. O & DO a

SE Geist Reservoir #33 NW 795 fl) Q.

790

3D A 785 UJ CO UJ

780 O 8

Q. 775 § fl) U_ 0» z~ i 770 O

1980 Fathometer profile UJ 765 1996 Bathymetry UJ Vertical exaggeration x 20 ° Intersection with bathymetry transect 760 200 400 600 800 1,000 1,200 1,400 1,600 HORIZONTAL STATION, IN FEET

Figure 28. Cross section #33 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. Geist Reservoir #36 N 10 795

LLJ 790 LLJ LLJ LLJ LL 21 C0 0(lr. 785

CC LLJ § 780 ? ^ LLJ LL LLJ O LL 10 775 £ LLJ 1980 Fathometer profile 5t 15 770 - 1996 Bathymetry Vertical., . , exaggeration x 20~i ° Intersection with bathymetry transect LLJ 20 I i I_____ 765 I 200 400 600 800 1,000 1.200 1,400 O HORIZONTAL STATION, IN FEET (0 o i

30 Figure 29. Cross section #36 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation (D (0 (D project) and a cross section from the bathymetric surface computed from the 1996 survey. i 00

to

to SE Geist Reservoir #37 NW Q. 795

UJ 790 > 1- I I UJ _J LJJ I UJ Oc 785 i55 -V ~ --e ~ e ^-e-^ - =&**' CO ? ^-^ _ *>»-« o e o ,_ ^^fj-^i^-^*"^ z UJ o . 5 _ 780 > rr O UJ I % ^ 10 775 < U*Q. £ : - ti U- -. UJ O 15 770 z"U. I . Q- 20 j 765 0 UJ 1980 Fathometer profile - Q ^ 25 1996 Bathymetry - 760 UJ Vertical exaggeration x 20 ; ° Intersection with bathymetry transect I UJ 3ft i , i , i , i . i i i . i . i . i . " 755 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 HORIZONTAL STATION, IN FEET

Figure 30. Cross section #37 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation project) and a cross section from the bathymetric surface computed from the 1996 survey. sw Geist Reservoir #39 NE ; ' i ' i i ' i ' i ' i i i i i ; f&> _J LLJ 1- _ 790 ^ LLJ "^ LLJ Sand Bar LL 0( 785TBfi 03m Z LLJ jg . ; " 780 §

_ ' > 10 775 LU LL. LLJ O LL X . -f n~ - 770 Q

LLJ ^^ IQAft1 9OU Fattv^motor all IwlllOWJl l/IUIHOnrnfilo . P Q < o 20 - 1996 Bathymetry ~ 765 S Vertical exaggeration x 20 1 _J ° Intersection with bathymetry transect - LLJ 25 1,1,1,1,1,1,1,1,' 7fin 200 400 600 800 1,000 1,200 1,400 1,600 1,800 HORIZONTAL STATION, IN FEET o (D

3D Figure 31. Cross section #39 of Geist Reservoir, central Indiana, from a 1980 fathometer profile (Indianapolis Water Company sedimentation (D (0 (D project) and a cross section from the bathymetric surface computed from the 1996 survey. O